Light based additive manufacturing methods employ a photo-curable resin in place of a thermal-sensitive filament. This liquid resin contains photosensitive monomers that polymerize when exposed to light of sufficient energy. Light based additive manufacturing methods use stereo lithography a technique where a rastering laser system directs a focused beam throughout a plane in the resin. By defining where the laser will contact the resin, a desired image or pattern can be “drawn” onto a build plate by selective polymerization of the resin in that plane. The pattern “drawn” into the resin is a cross sectional area of one particular layer of the three-dimensional object. By coordinating successive image exposures with incremental motion along an axis normal to the area of the image, an entire three-dimensional object can be fabricated.
Some systems use Digital Light Processing (DLP) and Liquid Crystal Display (LCD) systems as part of additive manufacturing. Digital Light Processing allows one to control an array of micromirrors that, when actuated, reflect light through projection optics. The result is a digital mask where each micromirror represents one pixel of a particular image. The implication is that now an entire cross sectional area of resin can be exposed at once, which reduces the time it would take to produce one layer of the object. Additionally, this method provides higher spatial resolution, since the spot size of each pixel is generally smaller than the spot size of a traditional stereo lithography laser.
Again, the coordinated exposure of successive images with the progressive motion of the build plate allows a three-dimensional object to be created.